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Revisions to the Northeastern Aquatic Habitat Classification

Revisions to the Northeastern Aquatic Habitat Classification

This project updated the 2008 Northeastern Aquatic Habitat Classification (NAHCS) prepared by The Nature Conservancy and the Northeast Association of Fish and Wildlife Agencies (NEAFWA). The updates added a tidal component to the classification of streams and rivers and a mapped classification of lakes; the lake classification was revised in 2015.

Abstract:

In 2008, The Nature Conservancy (TNC) and the Northeast Association of Fish and Wildlife Agencies (NEAFWA) completed the Northeastern Aquatic Habitat Classification (NAHCS) for 13 northeastern states (Olivero and Anderson, 2008). In the process of using the classification system and developing the habitat guide, two limitations were noted by the users: 1) the current system did not classify tidal systems and 2) it did not include a lake classification. This project addressed these limitations and updated the GIS data and a habitat guide that are available from TNC's Conservation Gateway:

Tidal: Tidal streams and rivers of the northeast support a unique assemblage of aquatic biological communities and are utilized as nursery areas, refuges, and important food sources for a variety of coastal, marine, and diadromous species. We collected and analyzed available data such as available diadromous fish distributions, tidal and brackish wetland occurrences, and estuary chemistry information, to accurately map the landward extent of these tidal stream and river habitats. The reviewed and finalized types were integrated into the GIS dataset and habitat guide.

Lakes: The lakes dataset was missing information on lake depth, a critical variable related to lake stratification and the presence of permanent cold water habitats in a lake. In 2011 EPA released a new data set of predicted lake depth for the region (Hollister et al. 2011). The new dataset estimates maximum depth from the slope of the surrounding topography for all lakes in the 1:100,000 National Hydrography Dataset (NHD+). The results have been well received. We obtained EPA’s predicted lake depth and morphology dataset, and evaluated its usefulness for estimating lake stratification and depth. We also compiled other newly available geospatial regional lake datasets, such as the National Lake Assessment water chemistry data. We reconvened the science steering committee to guide development of a regional lake classification and review final classification maps and descriptions.

Other Investigators:

Other Organizations:

Project Status:

The Nature Conservancy released the final report and datasets in January 2016. After considering 15 different lake classifications and assessments from across the region, the project leaders elected to focus on four key classification variables: 1) temperature class (four classes: very cold, cold, cool, warm); 2) alkalinity class (three classes); 3) trophic state class (four classes: oligotrophic, mesotrophic, eutrophic, and hypereutrophic); and 4) depth. A preliminary draft was released in late 2014, and revised and re-released after updating based on stakeholder and partner feedback.

Review by partners of the 2014 version of the report and datasets identified additional lake depth data and raised some ideas for refining the classification. TNC finished revising the classification based on the new information in December 2015. In January 2016, TNC completed the set of materials that describes the results. All project products, including a web mapper tool, spatial data, and reports, are now available from TNC's Conservation Gateway webpage.

The Nature Conservancy staff Mark Anderson and Arlene Olivero demonstrated how to apply the classification system for more effective conservation of aquatic ecosystems in the northeast during a (recorded) webinar in May 2016.

Links to Products:

The final report, data, a guide describing each classified habitat type, and web mapper are available from the project's Conservation Gateway page.

Watch the webinar featuring TNC staff Mark Anderson and Arlene Olivero demonstrated how to apply the classification system for more effective conservation of aquatic ecosystems in the northeast (recorded May 2016).